The present invention relates to a structure of a gilding apparatus for performing a gilding treatment by jetting a gilt liquid in a metalizing step of a semiconductor substrate.
In a conventional gilding apparatus of this type, as shown in FIGS. 4A, 4B, and 5, a cup-like tank 2 has a gilt liquid supply port 3, an anode electrode 5, and a semiconductor substrate support member 18, and the cup-like tank 2 is integrated with an outer tank 1. A gilt liquid 11 having a temperature controlled by a pump 9 is supplied from the gilt liquid supply port 3 to the cup-like tank 2 through a filter 8, and the gilt liquid 11 is jetted through the anode electrode 5. A semiconductor substrate 6 having a lower surface to be treated is supported by the semiconductor substrate support member 18 to be close to an upper opening 2a of the cup-like tank 2. A head member 10 vertically moved by a lifting mechanism member 17 through a base plate 16 is moved downward to be set and brought into contact with the semiconductor substrate 6, and a cross-shaped and leaf-spring-like cathode electrode 4e (shown in FIG. 4B) arranged on the heat member 10 is brought into contact with the semiconductor substrate 6 and is urged against the lower surface of the semiconductor substrate 6. A potential difference is applied between the anode electrode 5 and the cathode electrode 4e, thereby performing a gilding treatment.
In another structure, as shown in FIG. 6, a pin-like cathode electrode 4f is brought into contact with and urged against a semiconductor substrate 6 by elastic forces of springs, and a potential difference is applied between the anode electrode 5 and the cathode electrode 4f, thereby performing a gilding treatment.
In the above conventional gilding apparatus, since the cathode electrode using an elastic force of a spring is used as the contact portion on the cathode side, the elastic force does not easily have uniformity and resistances of the contact portions between a plurality of spring-like cathode electrodes and the semiconductor substrate are different from each other. When a gilding treatment is performed in this state, a gilt thickness is increased near a position having a low contact resistance, and a gilt thickness is decreased near a position having a high contact resistance, thereby varying the gilt thickness on the plated surface of the semiconductor substrate. Furthermore, a surface with which the cathode electrodes are in contact and which is to be plated tends to be plated thick, and the gilt thickness is disadvantageously varied.